Abstract: [Objective] Based on the trunk's shape and terrestrial laser scanning (TLS) data, the DBH, height and location of individual tree were estimated in the mountainous forests including natural forest stands and Cunninghamia plantation stands of Yunnan Province.[Method] DBH and height of individual tree were extracted by merged and single station TLS data. Location and DBH of individual tree were detected and extracted by applying a Hough transform algorithm coupled with trunk's shape. Then, tree height was estimated via trunk's direction and vertical distribution of canopy.[Result] 1) Based on multiple stations TLS data, the accuracy of tree identification was about 81% in the natural forest stands, with complicated stand structures and compositions. For the single station TLS data, the accuracy of tree identification decreased with the increasing TLS data area. The acquisition of single station TLS data was much easier than that of multiple stations. 2) Mosaicked multiple stations data provided higher accuracies of DBH and basal area of breast-height estimation, as compared to single station data. It was better to use the averages of multiple stations data to derive DBH and basal area of breast-height than single station data. It was more suitable to use data collected within a radius of 10 m to estimate DBH and basal area of breast-height than those collected within 5 m and 15 m radii. 3) The tree height estimation (R²=0.94,RMSE=0.96 m) of the plantations was more accurate than that (R²=0.77,RMSE=1.46 m) of the natural forests.[Conclusion] According to the feature along trunk, the most detected circle out of trunk could be deleted. This improved the estimating accuracies of tree detection, DBH and tree height. Locating single trunks and estimating DBH and height of individual trees were greatly dependent upon stand structural conditions and distributions of scanning stations. The merged multi scan TLS data extracted the most accurate result compared with averaged multi scan and single scan TLS data. The single scan TLS data showed occasional result.

Key words: terrestrial laser scanning, subtropical forest, DBH, tree height, basal area of breast-height